Rapid coagulation-flocculation and sedimentation type waste water treatment method

ABSTRACT

The present invention relates to a high speed coagulant-flocculant and sedimentation method for treating waste water, which permits a speedy treatment of waste water including stormwater runoff and also permits a valuable reuse of the sludge produced in the course of treatment. According to the present invention which achieves the object as described above, there is provided a method for treating waste water based on a high speed coagulation-flocculation and sedimentation which method is conducted in an arrangement for treating waste water based on a high speed aggregation and sedimentation, comprising a mixing tank, agitating tank, polymer aggregation tank and sedimentation tank in successive connection in that order, said arrangement being provided with transporting lines for transporting to the mixing or agitating tank the sludge produced in the sedimentation tank, and which method comprises introducing into the mixing tank the aggregating agent based on clay minerals, including zeolite or bentonite as the main component, introducing into the agitating tank an inorganic coagulant, and introducing into the polymer aggregation tank a polymeric flocculant on one hand, and introducing a combination of glass particle and kieselguhr into at least one of the mixing, agitating and polymer aggregating tank to convert the sludge resulted from treating the waste water into reusable porous ceramics on the other hand.

FIELD OF THE INVENTION

The present invention relates to a high speed coagulation-flocculationand sedimentation method for treating waste water and particularly to anovel high speed coagulation-flocculation and sedimentation method fortreating waste water, which permits a speedy treatment of waste waterincluding stormwater runoff and also permits a valuable reuse of thesludge produced in the course of treatment.

BACKGROUND OF THE INVENTION

Generally, the waste water is discharged after it was purified through aseries of treatment steps in a waste water treatment station including asewage treatment station, nightsoil treatment station and the like,wherein the waste water is first freed of the solid matter, floatingmatter, fatty matter and the like and then is subjected to a secondaryor tertiary treatment as required by a desired water quality standard.

The water purified through such treatments should meet the requiredquality criteria, wherein the quantity of nitrogen and phosphorus whichact as important factors for the eutrophication of the water is no lessimportant than BOD, COD or the like. Because particularly the phosphorusof them is contained much higher in quantity in the influent water alongwith stormwater runoff from the ground surface than in the waste wateritself, its effective removal calls for not only the treatment of thewaste water resulting from point sources of contamination but also thetreatment of stormwater runoff streams. However, the conventional wastewater treatment processes mostly depended on a normal activated sludgeprocess or extended aeration process, wherein the removal efficiency interm of total phosphorus amounted to so low as 10-30%. In addition,there was caused a problem, specially because the stormwater runoffstreams at the time of rainfall were left to discharge withouttreatment.

On the other hand, as a most effective method of removing the phosphorusin the waste water, there is widely used the coagulation-flocculationand sedimentation method based on the use of coagulant. However, thismethod is associated with a problem in that an additional cost isrequired to treat the sludge which is inevitably produced as the resultof the process and furthermore a secondary environmental pollution dueto the sludge is caused.

SUMMARY OF THE INVENTION

The object of the present invention, which invention was created toresolve the above-described problems of the conventional art, is toprovide a method for treating waste water based on a high speedcoagulation-flocculation and sedimentation which permits a high speedtreatment of waste water including stormwater runoff and an effectiveremoval of phosphorus and also permits a valuable reuse of the sludgeproduced in the course of waste water treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of an arrangement for treating waste waterbased on high speed coagulation-flocculation and sedimentation accordingto the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention which achieves the object asdescribed above, there is provided a method for treating waste waterbased on a high speed coagulation-flocculation and sedimentation whichmethod is conducted in an arrangement for treating waste water based ona high speed coagulation-flocculation and sedimentation, comprising amixing tank, agitating tank, polymer aggregation tank and sedimentationtank in a successive connection in that order, said arrangement beingprovided with transporting lines for transporting to the mixing- oragitating tank the sludge produced in the sedimentation tank, and whichmethod comprises introducing into the mixing tank the coagulant based onclay minerals, including zeolite or bentonite as the main component,introducing into the agitating tank an inorganic aggregating agent, andintroducing into the polymer aggregation tank a polymeric flocculant onone hand, and introducing a combination of glass particle and kieselguhrinto at least one of the mixing-, agitating- and polymer aggregatingtank to convert the sludge resulted from treating the waste water intoreusable porous ceramics on the other hand.

According to another aspect of the present invention, there is provideda method for treating waste water based on a high speed coagulation andsedimentation which method is conducted in an arrangement for treatingwaste water based on a high speed coagulation and sedimentation,comprising a mixing tank, agitating tank, polymer aggregation tank andsedimentation tank in a successive connection in that order, saidarrangement being provided with transporting lines for transporting tothe mixing- or agitating tank the sludge produced in the sedimentationtank, and which method comprises introducing into the mixing tank theglass particles with a particle size of 20-200 μm, introducing into theagitating tank an inorganic coagulant, and introducing into the polymeraggregation tank a polymeric flocculant on one hand, and introducing akieselguhr into at least one of the mixing-, agitating- and polymeraggregating tank to convert the sludge resulted from treating the wastewater into reusable porous ceramics on the other hand.

According to still other aspect of the present invention, there isprovided a method for treating waste water based on a high speedcoagulation-flocculation and sedimentation which method is conducted inan arrangement for treating waste water based on a high-speedcoagulation-flocculation and sedimentation, comprising a mixing tank,agitating tank, polymer aggregation tank and sedimentation tank in asuccessive connection in that order, said arrangement being providedwith transporting lines for transporting to the mixing- or agitatingtank the sludge produced in the sedimentation tank, and which methodcomprises introducing into the mixing tank the aggregating agent basedon clay minerals, including zeolite or bentonite as the main component,introducing into the agitating tank an inorganic coagulant, andintroducing into the polymer aggregation tank a polymeric flocculant andintroducing a mixture of glass particles with a particle size of 20-200μm and kieselguhr to convert the sludge resulted in the sedimentationtank into reusable porous ceramics.

According to further aspect of the present invention, there is provideda method for treating waste water based on a high-speedcoagulation-flocculation and sedimentation which method is conducted inan arrangement for treating waste water based on a high speedcoagulation-flocculation and sedimentation, comprising a mixing tank,agitating tank, polymer aggregation tank and sedimentation tank in asuccessive connection in that order, said arrangement being providedwith transporting lines for transporting to the mixing- or agitatingtank the sludge produced in the sedimentation tank, and which methodcomprises introducing into the mixing tank the glass particles with aparticle size of 20-200 μm, introducing into the agitating tank aninorganic coagulant, and introducing into the polymer aggregation tank apolymeric flocculant, and introducing a kieselguhr to convert the sludgeresulted in the sedimentation tank into reusable porous ceramics.

DETAILED DESCRIPTION OF THE INVENTION

Now, the present invention is described below in detail. FIG. 1 shows anarrangement for treating waste water based on rapidcoagulation-flocculation and sedimentation according to the presentinvention.

The rapid coagulation-flocculation and sedimentation type waste watertreating method according to the present invention is conducted in anarrangement which comprises a mixing tank, agitating tank, polymeraggregation tank and sedimentation tank in a successive connection inthat order, and which is provided with transporting lines fortransporting to the mixing- or agitating tank the sludge produced in thesedimentation tank, as depicted in FIG. 1. This arrangement for treatingwaste water may be applied to the treatment of sewage water in a sewagetreatment station, the treatment of the muddy water resulting fromconstructing work or lake dredging, or the treatment of stream waterflowing into a lake, river or sea.

In the mixing tank of such a waste water treating arrangement accordingto the invention, the aggregating agent based on clay mineral, havingzeolite or bentonite as the main component, is introduced and subjectedto mixing. As this aggregating agent, Aqua #219(supplied by JeongkwangAqua Co. Ltd. KR) is recommended. In the mixing tank, the aggregatingagent is blended and dissolved effectively and is given enough retentiontime, for example 3 minutes, to have effective contact with the wastewater to be treated. The organic matter, nitrogen and phosphoruscompounds contained in the waste water are adsorbed in the aggregatingor flocculating agent and suspended in the water. As the above-mentionedclay type aggregating agent containing mostly zeolite or bentonite ishigh in density, it contributes to the increase in the density ofresulting aggregated matter and thus the acceleration of its settlingvelocity. In such a manner, the presence of the aggregating agent playsits role of forming aggregates, resulting in the effective removal ofheavy metals and phosphorous components.

In the agitating tank, inorganic coaguant is introduced to make sure thecoagulation of the suspended matter produced in the foregoing mixingtank so that precipitate including the heavy metals and phosphorus maybe formed. As the inorganic aggregating agent for use in such anagitating tank, the conventional one can be used and preferably alum(aluminium sulfate) or the mixture of alum and ferric chloride at 7:3may be used. Thus, in this agitating tank, the separated particlesproduced in the above-mentioned mixing tank are flocked together withthe aid of inorganic coagulant and suspended or partially buoy up asflocculant matter. The reaction of producing the sediment of phosphortaking place in the agitating tank may be expressed as in the followingschemes:

However, because AlPO₄ is unstable at about pH of 7, it is known thatthe phosphorus compound is precipitated in the form ofAl_(y)PO₄(OH)_(3y−3). In this case, the formation reaction for thephosphorous precipitate is known to take place as follows:

In addition, in case FePO₄ aggregates with ferric chloride as well, theresulting form is known generally as Fe_(y)PO₄(OH)_(3y−3).

Next, the polymer aggregation tank acts to form the aggregates perfectand as large as over several hundred micrometers from fine aggregates topromote the settling velocity. To that end, polymeric flocculant isintroduced there. As the polymeric flocculant, the polyacrylamide-basedagent, which is one of anionic polyelectrolytes, for example, “SA 307”(manufactured by Songwon Ind. Co. Ltd.) or “YA 712” (manufactured bylyang Chem. Co. Ltd.) may be preferably used.

Finally, in the sedimentation tank, the precipitates formed in thepreceding tanks are settled and removed, wherein a speedy settling at athroughput of over 300 m/day in conjunction with a high efflux rate oftreated water may be expected by employing an inclined plate settlingtank equipped with a scraper. Further, transfer lines for recycling someof the sludge in the sedimentation tank to the preceding tanks areprovided, so that the particles included in the sludge may be repeatedlyused to increase the useful particle density in the tanks while reducingthe fresh use of the agent, whereby aggregating velocity is increasedwith the floating particles abundantly supplied and settling property offlocks are also improved.

On the other hand, according to the present invention, glass particlesand kieselguhr are added in one of the mixing, agitating and polymeraggregating tanks. This is intended to reuse the sludge produced in thewaste water treating arrangement as porous ceramics. Generally, theporous ceramics are used in a variety of applications such as artificialsoil, various filters, culture media, carriers for microbes or the like,heat insulators, water preserving material, adsorbent, odor adsorbingmaterial and the like.

The above-mentioned kieselguhr is used to impart to the porous ceramicsan excellent void proportion which is made possible by the fact that thefine pores present in the particles of kieselguhr remain unchanged evenafter the sintering process. The glass particles act to join togetherthe particles of sludge or kieselguhr three-dimensionally by softeningor melting during the sintering process, wherein the glass can besoftened for its intended purpose in a heat treatment at a temperatureas low as 700-850° C., approximately the glass softening point, incomparison to the higher temperature ranging from 1000 to 1300° C. forsintering kieselguhr or zeolite in the production of porous ceramics.Therefore, the combined use of glass and kieselguhr according to theinvention permits saving in energy for the manufacture of porousceramics due to the low softening point of the glass compared with thecase of no glass component and at the same time the maintenance of highporosity compared with the case of absence of glass particle andkieselguhr.

While the addition of glass and kieselguhr may be made either at thestep of rapid mixing or rapid agitation, it is more preferable to addthe mixture along with an inorganic coagulant agent into the agitatingtank as the suspended matter produced in the prior mixing tank canthereby be aggregated more reinforcedly and effectively to gain thespeeded settling velocity in this agitating tank. The average particlesize of glass particle and kieselguhr lies preferably within the rangeof between 20 and 200 μm. When the size is below the lower limit of 20μm, the settling velocity of the sediment is lowered, while above theupper limit of 200μm, the ultimate porous ceramic product from thesludge is deteriorated, as the moldability of porous ceramics becomespoor and the sintering reaction is negatively influenced by the presenceof coarse particles. Regarding the mixing ratio of the glass particle,the amount of glass relative to the other components excluding theglass, i. e. the clay mineral-based aggregating agent containingkieselguhr, zeolite or bentonite as the principal component and theother additives such as alum, ferric chloride and polymer aggregatingagent ranges, in weight, from 7:3 to 3:7. When the amount of glassparticle is excessive relative to the other additives including thekieselguhr and the like, the resulting porous ceramics become poor inporosity. On the other hand, in the case of the excessive otheradditives, the disadvantage is caused because the heat treatment isrequired up to the sintering temperature for the kieselguhr or the likewhich is considerably higher than the softening point of glass.

On the other hand, the sludge is collected, dewatered and molded into adesired form e. g. a pellet form and then subjected to a sintering ovenin which sintering process is conducted at a temperature of 700-850° C.near the softening point of glass to produce the desired porousceramics. The porous ceramics so produced have an excellent physicalproperty as will be described later.

Furthermore, according to an aspect of the invention, into theabove-mentioned mixing tank there is introduced glass powder instead ofthe clay mineral based aggregating agent including zeolite or bentoniteas the main component. This is based on the fact that the sole glassparticle can compare with the mineral based aggregating agent in thecapability of boosted aggregation to permit a high settling velocitycorresponding to the throughput of over 300 m/day under effectiveremoval of organic matter and phosphorus component. In this case, thekieselguhr may also be added in any one of the mixing, agitating andpolymer aggregating tanks.

Moreover, it is also possible to admixed the glass particle andkieselguhr directly with the produced sludge rather than put them in thecourse of treating the waste water. In that case, the kieselguhr may beadded either into the sedimentation tank where the produced sludge isdeposited or at a third place to which the deposited sludge has beentransferred from the sedimentation tank.

Optionally, the clay mineral based aggregating agent including zeoliteor bentonite as the main component may be replaced by the glass particlein the intermediate steps of treating the water and the kieselguhr canbe added to the sludge in the sedimentation tank. In that case too, thekieselguhr may be added either into the sedimentation tank where theproduced sludge is deposited or at a third place to which the depositedsludge has been transferred from the sedimentation tank.

EXAMPLE 1

A test was conducted at a waste water treatment facility based on a highspeed coagulation-flocculation and sedimentation according to theinvention at an overflow rate of 300 m/day by using as the raw water thebiologically treated water from at Sungki sewage treatment stationlocated in Inchon, Korea. The recycling ratio of sludge from thesedimentation tank was kept at 5%, in the mixing tank Aqua #219 wasadded in varied quantity and subsequently mixed for a period of 3minutes, and in the agitation tank the mixture of alum and ferricchloride at a blending ratio of 7:3 was added in varied quantity andagitated for a period of 1 minute. Thereafter, YA 712 was added in thepolymer aggregation tank at an amount of 1 mg/l and caused to aggregatefor a period of 3 minutes. The result of analysis for the water sotreated is listed in the following table 1.

TABLE 1 (1) (2) (3) Raw Treated Raw Treated Raw Treated Article waterwater water water water water Additive Aqua#219 (mg/L) 30 50 70 Alum(mg/L) 35 35 49 Ferric chloride (mg/L) 15 15 21 YA 712 (mg/L) 1 1 1Result of pH 6.7 6.5 6.3 treatment BOD (mg/L) 10.6 4.7 7.5 1.0 51.6 9.0removal eff. (%) 55.7 86.7 82.6 COD (mg/L) 29.2 6.5 23.4 3.5 74.6 13.3removal eff. (%) 77.7 85.0 82.2 T-P (mg/L) 2.99 0.25 2.16 0.20 4.37 0.41removal eff. (%) 91.6 90.7 90.6 T-N (mg/L) 24.5 20.5 20.3 16.5 13.9 11.2removal eff. (%) 16.3 18.7 19.4 SS (mg/L) 19 4.3 6 2.7 10.1 6.3 removaleff. (%) 77.4 55.0 37.4

Particularly, it is seen from the above table that regardless of theadded amount of Aqua #219, alum and ferric chloride, the removalefficiency for total phosphorus amounted to over 90% and the removalefficiencies for BOD and COD were also satisfactory.

EXAMPLE 2

A test was conducted at a waste water treating facility based on a highspeed coagulation-flocculation and sedimentation according to theinvention by using as the raw water the biologically treated water fromat Sungki sewage treatment station located in Inchon, Korea. In themixing tank, Aqua #219, glass particle with an average particle size of50 μm and kieselguhr with an average particle size of 40 μm were addedin varied quantity and subsequently mixed for a period of 3 minutes, andin the agitation tank the mixture of alum and ferric chloride at ablending ratio of 7:3 was added in varied quantity and agitated for aperiod of 1 minute. Thereafter, YA 712, an anionic polymer aggregatingagent (manufactured by lyang Chemical) was added in the polymeraggregation tank at an amount of 1 mg/l and caused to aggregate for aperiod of 3 minutes. The recycling ratio of sludge from thesedimentation tank to the mixing tank was kept at 5%, The result ofanalysis for the water so treated is listed in the following table 2.

TABLE 2 (1) (2) (3) Raw Treated Raw Treated Raw Treated Article waterwater water water water water Additive Aqua#219 (mg/L) 18 50 100 Glassparticle (mg/L) 24 66.7 133.3 kieselguhr (mg/L) 18 50 100 Alum (mg/L) 5035 70 Ferric chloride (mg/L) 0 15 30 YA 712 (mg/L) 1 1 1 Result of pH7.32 6.78 7.23 6.90 7.23 6.56 treatment BOD (mg/L) 26.7 10.3 16.2 5.116.2 1.2 removal eff. (%) 61.4 68.5 92.6 COD (mg/L) 37.6 14.5 29.1 8.129.1 3.2 removal eff. (%) 61.4 72.2 89.0 T-P (mg/L) 0.96 0.08 0.99 0.050.99 0.009 removal eff. (%) 91.7 95.0 99.1 T-N (mg/L) 17.8 14.9 20.415.5 20.4 15.2 removal eff. (%) 16.3 24.0 25.5

From Table 2, it is appreciated that in this case of adding furthercomponents of glass particle and kieselguhr the removal rate of totalphosphorus increased to over 95%.

EXAMPLE 3

Another test was conducted at a waste water treating facility asmentioned above by using as the raw water the biologically treated waterfrom Sungki sewage treatment station located in Inchon, Korea. In themixing tank, Aqua #219, glass particle with an average particle size of50 μm and kieselguhr with an average particle size of 40 μm were addedin varied quantity and subsequently mixed for a period of 3 minutes, andin the agitation tank the alum was added at a rate of 50 mg/l andagitated for a period of 1 minute. Then, YA 712 was added in the polymeraggregation tank at an amount of 1 mg/l and caused to aggregate for aperiod of 3 minutes. The recycling ratio of sludge from thesedimentation tank to the mixing tank was kept at 5%, The result ofanalysis for the water so treated is listed in the following table 3.

TABLE 3 Raw Article water (1) (2) (3) (4) Additive Aqua#219 (mg/L) 0 0 00 Glass particle 50 100 50 100 (mg/L) kieselguhr (mg/L) 0 0 50 50 Alum(mg/L) 50 50 50 50 YA 712 (mg/L) 1 1 1 1 Result of pH 7.32 6.89 6.976.69 6.21 treatment BOD (mg/L) 26.7 6.1 6.1 15.7 10.5 removal eff. (%)77.2 77.2 41.2 60.7 COD (mg/L) 37.6 19.5 14.5 22.7 21.1 removal eff. (%)48.1 61.4 39.6 43.9 T-P (mg/L) 0.96 0.16 0.09 0.09 0.09 removal eff. (%)83.3 90.6 90.6 90.6 T-N (mg/L) 17.8 15.5 14.9 14.8 14.6 removal eff. (%)12.9 16.3 16.9 18.0

Table 3 indicates that the removal efficiency of total phosphorus can beas high as 83% or more just with glass and kieselguhr without any Aqua#210. A comparison of the run (1) and (2) for the case of only glassshows the higher removal efficiency for COD, total phosphorus and totalnitrogen in the run (2) with higher quantity than in the run (1) withthe lower quantity. On the other hand, the comparison of the run (3) and(4) for the case of using the glass particle together with thekieselguhr shows that the increase in the quantity of glass has noappreciable effect on the removal efficiency of the total phosphorus andtotal nitrogen but minor effect on the removal efficiency for BOD andCOD. Comparing the run (1) for the case of using only glass particlewithout kieselguhr with the run (3) for the case of using the unvariedamount of glass particle and further the kieselguhr and the run (2) forthe case of using only glass particle without kieselguhr with the run(4) for the case of using the unvaried amount of glass particle andfurther the kieselguhr, it is appreciated that the runs (1) and (2) forthe case of no kieselguhr are more advantageous in the point of BOD andCOD but the runs (3) and (4) for the case of using kieselguhr are moreadvantageous in the point of the removal efficiency for the totalphosphorus and total nitrogen. The run (2) for the total quantity ofadded glass at 100 mg/l was approximately as effective as with regard tothe total phosphorus and total nitrogen but more effective with regardto BOD and COD than the run (3) for the same total quantity of additiveat 100 mgA but composed of the respective half of glass particle andkieselguhr.

EXAMPLE 4

A still other test was conducted at various flow rates of water at awaste water treating facility as mentioned above by using as the rawwater the biologically treated water from Sungki sewage treatmentstation located in Inchon, Korea. The recycling ratio of sludge from thesedimentation tank to the mixing tank was kept at 5%. In the mixingtank, glass particle with an average particle size of 70 μm andkieselguhr with an average particle size of 50 μm were added each at 50mg/l and mixed at a rapid speed for a period of 3 minutes, and in theagitation tank the alum was added at a rate of 50 mg/l and agitated fora period of 1 minute. Then, YA 712 was added in the polymer aggregationtank at an amount of 1 mg/l and caused to aggregate for a period of 3minutes. The result of analysis for the water so treated is listed inthe following table 4.

TABLE 4 (1) (2) (3) Raw Treated Raw Treated Raw Treated Article waterwater water water water water Additive overflow ratio (m/day) 300 360420 Glass particle (mg/L) 50 50 50 kieselguhr (mg/L) 50 50 50 Alum(mg/L) 50 50 50 YA 712 (mg/L) 1 1 1 Result of pH 6.7 6.6 6.5 treatmentBOD (mg/L) 22.7 3.9 29.6 4.7 38.2 9.0 removal eff. (%) 82.8 84.1 76.4COD (mg/L) 17.5 10 16 10 30 16 removal eff. (%) 42.9 37.5 46.7 T-P(mg/L) 0.97 0.10 0.74 0.11 1.06 0.07 removal eff. ( %) 89.7 85.1 93.4T-N (mg/L) 13.6 11.3 20.5 16.9 30.7 27.7 removal eff. (%) 16.9 17.6 9.8SS (mg/L) 11.5 2.0 11 4.8 43 5.0 removal eff. (%) 82.6 56.4 88.4

It is seen from Table 4, that addition of only glass particle andkieselguhr without Aqua #219 in the mixing tank still leads to theattainment of the removal efficiency for the total phosphorus and totalnitrogen at over 85%. An increase in the overflow rate appeared to befavorable to the treatment result.

EXAMPLE 5

Another test was conducted at a waste water treating facility asmentioned above by using the biologically treated water from Sungkisewage treatment station located in Inchon, Korea. At the overflow rateof 300 m/day(treating rate of 5 m³/hr) the sludge was returned from thesedimentation tank to the mixing tank at the recycling ratio of 5%. Inthe mixing tank, glass particle with an average particle size of 50 μmwas added and mixed at a rapid speed for a period of 3 minutes, and inthe agitation tank the alum was added and agitated rapidly for a periodof 1 minute. Then, YA 712 was added in the polymer aggregation tank atan amount of 1 mg/l and caused to aggregate for a period of 3 minutes.The result of analysis for the water so treated is listed in thefollowing table 4.

TABLE 5 (1) (2) (3) Raw Treated Raw Treated Raw Treated Article waterwater water water water water Additive Glass particle (mg/L) 30 50 70Alum (mg/L) 50 50 50 YA 712 (mg/L) 1 1 1 Result of pH 6.8 6.5 6.2treatment BOD (mg/L) 20.7 10.2 38.2 4.8 27.5 4.3 removal eff. ( %) 50.787.4 84.4 COD (mg/L) 29.3 14.5 42.5 20.5 24.5 7.5 removal eff. (%) 50.551.8 69.4 T-P (mg/L) 1.64 0.52 1.35 0.13 1.14 0.18 removal eff. (%) 68.390.4 84.2 T-N (mg/L) 17.0 12.3 15.5 10.7 10.0 5.8 removal eff. (%) 27.631.0 42.0 SS (mg/L) 11.5 7.0 6.8 2.48 27.4 6.4 removal eff. (%) 39.164.7 76.6

Table 5 indicates that even in the case only the glass particle wasadded and mixed, a high removal efficiency of over 84% could be attainedwith enough use of 50 mg/A or more.

As can be appreciated from the above-described examples, the high speedcoagulation-flocculation and sedimentation which the present inventionseeks can be achieved through various routes which includes adding theglass particle only, the combination of glass particle and kieselguhr,or the combination of Aqua #219, glass particle and kieselguhr.Moreover, the addition of glass particle and kieselguhr which waspartially intended to reuse the sludge showed no appreciable detrimentalaction regarding the water treatment as a whole but instead had afavorable effect on the treating capability of waste water in comparisonwith the conventional art.

EXAMPLE 6

A test was conducted at a waste water treating facility as mentionedabove by using as the raw water the biologically treated water fromSungki sewage treatment station located in Inchon, Korea. With therecycling ratio of sludge at 5%, in the mixing tank, Aqua #219, glassparticle with an average particle size of 50 μm and kieselguhr with anaverage particle size of 40 μm were added in varied quantity andsubsequently mixed together for a period of 3 minutes. In the agitationtank the alum and ferric chloride at a blending ratio of 7:3 were addedat various adding rates and agitated for a period of 1 minute. Then, YA712 was added in the polymer aggregation tank at an amount of 1 mg/A andcaused to aggregate for a period of 3 minutes. After the resultingsludge was dried, it was granulated to the particle size of 1 mm andheat treated at around 800° C. to thereby provide porous ceramics. Thephysical properties for the porous ceramics so obtained were measured asin the following table 5.

TABLE 6 Article (1) (2) (3) Additive Aqua #219 (mg/L) 18 50 100 Glassparticle (mg/L) 24 133.4 166.6 kieselguhr (mg/L) 18 50 100 Alum (mg/L)50 35 70 Ferric chloride (mg/L)  0 15 30 YA 712 (mg/L)  1 1 1 Result ofvoid proportion (%) 45.3 46.0 treatment Density (g/cc) 1.33 1.29Absorptivity (g/cc) 0.43 0.44

For the case under the article (1) in Table 6, it was almost impossibleto obtain porous ceramics under the condition tested at 800° C., becausethe glass particle used was so low as to amount to only less than 30%based on the other additives. It is seen that the porous ceramicsmanufactured under the articles (2) and (3), however, had excellentphysical properties in comparison with the conventional porous ceramicshaving the void proportion of 35 to 40%.

EXAMPLE 7

The sludge pertaining to the runs (3) and (4) in the foregoing Example 3was subjected to drying, formed into granules having an average particlesize of 1 mm and then sintered at the temperature of 800° C. to provideporous ceramics. The physical properties for the porous ceramics soobtained were measured as in the following table 7.

TABLE 7 Article (3) (4) Additive Aqua #219 (mg/L) 0 0 Glass particle(mg/L) 50 100 kieselguhr (mg/L) 50 50 Alum (mg/L) 50 50 YA 712 (mg/L) 11 Result of void proportion (%) 48.1 45.7 treatment Density (g/cc) 1.171.21 Absorptivity (g/cc) 0.46 0.44

The table shows some physical properties of the porous ceramicsmanufactured from the sludge which resulted from treating the wastewater by using glass particle instead of the clay type mineral in themixing tank. It is clear that the decreased use of the kieselguhrrelative to other components leads to the poor porosity of ceramicproducts.

As described already, the use of the glass particle and kieselguhr forreuse of the sludge did not reduce the treating ability of waste waterbut rather increased it to exceed the conventional method as may beconfirmed from the test results for Example 1 through Example 5. Thecase wherein the glass particle instead of the clay type mineralincluding zeolite and bentonite was used exhibited specially excellenttreatment results. It was also seen that the rapidcoagulation-flocculation and sedimentation type waste water treatmentmethod according to the present invention could limit the concentrationsof the total phosphorus and the phosphate form phosphorus tosatisfactory levels and particularly within 0.02 mg/l and 0.01 mg/Arespectively. The quality of the porous ceramics manufactured from thedisposable sludge which depended somewhat on the amount of the glassparticle and kieselguhr used but was irrespective of the time ofapplication of those mineral components was at least comparable with andin fact better than the conventional similar kinds.

The rapid coagulation-flocculation and sedimentation type wastewatertreatment method according to the present invention thus permitsthe removal of harmful components in the waste water including heavymetals and phosphorus through a rapid coagulation-flocculation andsedimentation and also permits reuse of the produced sludge as porousceramics.

In other words, the rapid coagulation-flocculation and sedimentationtype waste water treatment method according to the present invention isso excellent in treating speed and treating efficiency compared to aconventional method as to treat the total quantity of the river waterincluding stormwater runoff effectively and also contributes to theprevention of the secondary pollution by the sludge which is reused asvaluable product.

Further, the porous ceramics which are produced at a low cost accordingto the present invention are remarkably excellent in the physicalproperties.

It is to be understood that, while the invention was described withrespect to some specific examples, a variety of modifications andalterations would be possible to a man skilled in the art within thespirit of the invention and thus those modifications or alterations areto fall within the scope of the invention, which scope should be limitedonly by the attached claims.

What is claimed is:
 1. A method for treating waste water based on highspeed coagulation-flocculation and sedimentation which method isconducted in an arrangement for treating waste water based on a highspeed aggregation and sedimentation, comprising a mixing tank, anagitating tank, a polymer aggregation tank and a sedimentation tanksuccessively connected, said arrangement being provided withtransporting lines for transporting to the mixing or agita produced inthe sedimentation tank, comprising introducing into the mixing tank saidwaste water and an aggregating agent which is based on clay mineralsincluding zeolite or bentonite as a main component, introducing into theagitating tank said waste water and an inorganic coagulant, introducinginto the polymer aggregation tank said waste water and a polymericflocculent and introducing a combination of glass particles andkieselguhr into at least one of the mixing, agitating and polymeraggregation tanks to convert the sludge resulting from treating thewaste water into reusable porous ceramics.
 2. A method of claim 1wherein the average particle size of the glass particles and kieselguhrlies within the range of between 20 and 200 μm.
 3. A method of claim 2wherein the amount of glass relative to the other components excludingthe glass ranges, in weight, from 7:3 to 3:7.
 4. A method of claim 1wherein the amount of glass relative to the other components excludingthe glass, ranges in weight, from 7:3 to 3:7.
 5. A method of claim 1wherein the aggregating agent is a zeolite or bentonite.
 6. A method fortreating waste water based on high speed coagulation-flocculation andsedimentation process which method is conducted in an arrangement fortreating waste water based on high speed aggregation and sedimentation,comprising a mixing tank, an agitating tank, a polymer aggregation tankand sedimentation tank successively connected, said arrangement beingprovided with lines for transporting to the mixing, or agitating tanksludge produced in the sedimentation tank, and which method comprisingintroducing into the mixing tank said waste water and glass particleswith a particle size of 20-200 μm, introducing into the agitating tanksaid waste water and an inorganic coagulant, introducing into thepolymer aggregation tank said waste water and a polymeric flocculent andintroducing a kieselguhr into at least one of the mixing, agitating andpolymeric aggregation tanks to convert the sludge resulting fromtreating the waste water into reusable porous ceramics.
 7. A method fortreating waste water based on high speed coagulation-flocculation andsedimentation which method is conducted in an arrangement for treatingwaste water based on high-speed aggregation and sedimentation,comprising a mixing tank, an agitating tank, a polymer aggregation tankand a sedimentation tank in a successive connection in that order, saidarrangement being provided with transporting lines for transporting tothe mixing or agitating tank the sludge produced in the sedimentationtank, and which method comprises introducing into the mixing tank saidwaste water and an aggregating agent based on clay minerals, includingzeolite or bentonite as a main component, introducing into the agitatingtank said waste water and an inorganic coagulant, introducing into thepolymer aggregation tank said waste water and a polymeric flocculent,and introducing a mixture of glass particles with a particle size of20-200 μm and kieselguhr to convert the sludge resulted in thesedimentation tank into reusable porous ceramics.
 8. A method fortreating waste water based on high speed coagulation-flocculation andsedimentation which method is conducted in an arrangement for treatingwaste water based on high speed aggregation and sedimentation,comprising a mixing tank, an agitating tank, polymer aggregation tankand sedimentation tank in a successive connection in that order, saidarrangement being provided with transporting lines for transporting tothe mixing or agitating tank the sludge produced in the sedimentationtank, and which method comprises introducing into the mixing tank saidwaste water and glass particles with a particle size of 20-200 μm,introducing into the agitating tank said waste water and an inorganiccoagulant, and introducing into the polymer aggregation tank said wastewater and a polymeric flocculant, and introducing a kieselguhr toconvert the sludge resulted in the sedimentation tank into reusableporous ceramics.